The number 80991
80991 is a composite number with 6 divisors. Its prime factorisation is × 8999. Divisors (6): 1, 3, 9, 8999, 26997, 80991.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
80991 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
80991 is composite. Its prime factorisation is
- 3
The divisors add up to 117000; without 80991 itself that is 36009, so 80991 is deficient (36009 is less than 80991). Euler's totient φ(80991) = 53988 numbers up to 80991 share no factor with it.
- 4
The digits of 80991 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 89 steps to reach 1.
LaTeX source of the formulas on this page
\[ 80991 = 3^{2} \times 8999 \]80991 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 117000 |
| Euler totient φ(n) | 53988 |
| Square | 6559542081 |
| Cube | 531263872682271 |
| Square root | 284.589178 (= 3√8999) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 89 |
| Scientific notation | 8.0991 × |
80991 in other forms
| Form | Value |
|---|---|
| In words | eighty thousand nine hundred and ninety-one |
| Binary (base 2) | 10011110001011111 |
| Octal (base 8) | 236137 |
| Hexadecimal (base 16) | 13C5F |
| Base 3 | 11010002200 |
| As time | 80991 seconds = 22 h 29 min 51 s |
Is 80991 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (80991 ÷ 3 = 26997) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7. |
| 8 | No (remainder 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (80991 ÷ 9 = 8999) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 80991 a prime number?
No. 80991 = × 8999, so it is divisible by 3.
What are the factors of 80991?
1, 3, 9, 8999, 26997, 80991.
What is 80991 in binary?
10011110001011111 (hexadecimal 13C5F, octal 236137).
What is the square root of 80991?
About 284.5892, exactly 3√8999.
Is 80991 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 80991?
It is a composite number with 6 divisors.